Revealing a synergistic orbital coupling adsorption mechanism of the oxygen reduction reaction in dual-atom catalysts

Abstract

Dual-atom catalysts (DACs) have recently been active in various catalytic fields, such as the oxygen reduction reaction (ORR), but the underlying mechanism of the synergistic effect of DACs in regulating the catalytic performance has not been fully elucidated yet. To explore these, we constructed 406 DACs with a combination of dozens of metal elements on nitrogen-doped graphene (NDG) via high-throughput calculation, and accelerated the screening of DACs with outstanding ORR activity with the assistance of a crystal graph convolutional neural network (CGCNN) model. Based on the calculated results, a synergistic orbital coupling adsorption mechanism is proposed for DACs to explain the specific adsorption modes and orbital coupling formed between intermediate species (O₂ and OH) and dual-atoms during the adsorption process for the oxygen reduction reaction. Specifically, it is found that the orbital coupling between the intermediate species and active center will rely on the electron distributions of the d_xz, d_yz, and d_z² orbitals near the Fermi level of dual-atoms, which further dominate the adsorption strength of intermediate species, potential determining step, and catalytic activity. The present work offers new insights into the recognition of catalytic mechanisms of DACs, and provides guidance for the design of DACs.